Yes. Open-cell foam in a 2x4 interior partition wall cavity adds STC 5-7 to the assembly, a perceptible improvement that cuts perceived loudness by roughly 25 percent. For dedicated quiet rooms (home office, recording space, theater), pair open-cell with 5/8-inch Type X drywall and mass-loaded vinyl backing.
More detail
Sound transmission across walls is measured in STC (sound transmission class). Higher STC means more sound blocked. The standard 2x4 interior partition wall with empty cavity, 1/2-inch drywall both sides, has STC of about 33-35. Adding fiberglass batts brings it to STC 37-39. Adding open-cell foam brings it to STC 40-42. Adding closed-cell foam brings it to STC 36-38 (closed-cell is denser and acoustically more reflective, so its sound-blocking benefit is smaller than open-cell). The perceptual change. STC 35 means loud conversation is audible but not understood; STC 40 means loud conversation is muffled to barely audible; STC 45 means even loud music is just a thump. A 5-7 STC improvement is the difference between hearing your kid playing video games clearly through the bedroom wall and hearing it as ambient background noise. The Cincinnati interior-wall opportunity. Most Cincinnati 1990s and newer homes have interior partition walls with empty cavities (no insulation between bedrooms, between hallway and bedrooms). Adding open-cell foam to interior walls during a wall-cavity foam project for exterior walls is a low-cost upgrade ($0.50-$0.80 per sqft of wall surface) that produces noticeable comfort improvement. For dedicated quiet spaces. A home office, recording studio, or home theater benefits from a multi-layer approach. (1) Open-cell foam in the cavity. (2) 5/8-inch Type X drywall (denser than standard 1/2-inch). (3) Mass-loaded vinyl backing (sheet vinyl impregnated with metal salts, hung between the framing and the drywall). (4) Acoustic isolation clips that mechanically isolate the drywall from the framing. A wall assembly with all four reaches STC 50-55, which blocks essentially all conversational and most musical sound transmission. Cost: roughly $4-$8 per sqft of wall above the standard drywall and foam scope. Cincinnati installer note: a foam-only project provides 70 percent of the soundproofing benefit at 20 percent of the cost compared to a full acoustic-isolation assembly. Most Cincinnati homeowners get the quiet they want from open-cell foam in interior partitions alone; the full acoustic isolation is overkill for typical residential use.